Gluttonous cosmic ‘black widow’ is heaviest known neutron star

A spinning neutron star periodically swings its radio (green) and gamma rays (magenta) past Earth in this artist’s concept of a black widow pulsar. The pulsar heats the opposite side of its stellar partner to temperatures twice the surface of the sun and slowly evaporates. NASA/Goddard Space Flight Center/Handout via REUTERS

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WASHINGTON, July 29 (Reuters) – Astronomers have observed the most massive known example of an object called a neutron star, an object classified as a “black widow” that became particularly hefty by gobbling up most of the mass of a stellar companion trapped in an unhappy cosmic marriage.

The researchers said the neutron star, which spins wildly at 707 times per second, has a mass about 2.35 times that of our sun, giving it perhaps the maximum possible mass for such objects before they collapse to form a star. to form a black hole.

A neutron star is the compact collapsed core of a massive star that exploded as a supernova at the end of its life cycle. The one described by the researchers is a highly magnetized type of neutron star called a pulsar that unleashes beams of electromagnetic radiation from its poles. As it spins, these rays appear from an observer’s perspective on Earth to pulse — similar to the rotating light of a lighthouse.

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Only one other neutron star is known to spin faster than this one.

“The more massive the neutron star, the denser the material in its core,” said Roger Romani, director of Stanford University’s Center for Space Science and Astrophysics and co-author of the study published this week in the Astrophysical Journal Letters.

“So as the heaviest neutron star we know, this object presents the densest material in the observable universe. If it were heavier, it would collapse into a black hole, and then the stuff inside would be behind the event horizon, closed off from any event forever. observation,” Romani added.

The event horizon of a black hole is the point of no return beyond which everything, including light, is irreparably sucked up.

“Since we don’t yet know how matter works at these densities, the existence of this neutron star is an important probe of these physical extremes,” Romani said.

The neutron star, located in our Milky Way galaxy toward the constellation Sextans and officially called PSR J0952-0607, is about 20,000 light-years from Earth, Romani said. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). The researchers studied it using the Keck I telescope in Hawaii.

Stars that are about eight or more times the mass of the sun transform hydrogen into heavier elements through thermonuclear fusion in their cores. When they build up about 1.4 times the mass of our sun in iron, that core collapses into a neutron star only about the size of a city, and the rest is blown away in the supernova explosion.

This neutron star inhabits what is called a binary system, orbiting another star. The neutron star is a species called a “black widow,” named in honor of female black widow spiders that eat their male partners after mating.

It was apparently born with the usual mass of a neutron star, about 1.4 times that of our sun, but its gravity stripped material from its companion star, allowing it to grow to a mass that was seemingly at the upper limit before physics would dictate a collapse in a black hole, the densest of all known objects.

Its companion star has been nearly stripped bare and may have lost 98% of its mass to the black widow, giving it about 20 times the mass of our solar system’s largest planet, Jupiter — a far cry from its original size.

“In a case of cosmic ingratitude, the black widow’s pulsar, which has devoured much of its mate, is now heating and vaporizing the companion to planetary masses and perhaps complete destruction,” added study co-author Alex Filippenko, a University of California, Berkeley, professor of astronomy.

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Reporting by Will Dunham; Editing by Lisa Shumaker and Sandra Maler

Our standards: The Thomson Reuters Trust Principles.

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